Brightness Temperature

Measurement Description
Brightness Temperature

The brightness temperature is a measurement of the radiance of the microwave radiation traveling upward from the top of the atmosphere to the satellite, expressed in units of the temperature of an equivalent black body.  The brightness temperature (or TB ) is the fundamental parameter measured by passive microwave radiometers.  The brightness temperatures measured at different microwave frequencies  are used at Remote Sensing Systems to derive wind, vapor, cloud, rain, and SST products. 

Geophysical Retrievals

Measurement Description
Atmospheric Water Vapor

Total column water vapor (or Total Precipitable Water) is a measure of the total gaseous water contained in a vertical column of atmosphere. This quantity can be measured using microwave radiometers over the world's oceans. Water vapor is measured in linear units, millimeters (mm), the depth the water would be if condensed to liquid form. Using the density of water, we can also report vapor as kg/m2 = 1 mm, or g/cm2 = 10 mm.


The Version-2 Cross-Calibrated Multi-Platform (CCMP) wind product consists of four-times-daily, 6-hourly gridded analyses of surface vector winds produced using satellite, in situ and model data.

Cloud Liquid Water Content

Cloud Liquid Water Content is a measure of the total liquid water contained in a vertical column of atmosphere, and does not include solid water (snow or ice).  Decades of satellite microwave radiometer cloud data are available for study.  Units of measurement are mm, the depth of the liquid water in the vertical column.  Using the density of water, we can also report cloud liquid water as kg/m2 = 1 mm, or g/cm2 = 10 mm

Rain Rate

Precipitation is a key hydrological and climate variable that includes both liquid (rain) and solid (snow and ice) forms.  RSS provides estimates of the surface rain rate over the global oceans derived from microwave radiometers.  Rain is highly variable in both time and space.  Units are mm/hr.

Sea Surface Temperature

Sea Surface Temperature (SST) can be measured by microwave radiometers with lower frequency channels (TMI, AMSR-E and WindSat).  SST data are available from 1997 onward.  Using a diurnal model, our Optimal Interpolated SSTs are corrected to represent a foundation temperature, or a diurnally corrected surface layer temperature.

Upper Air Temperature

The temperature of the air well above Earth's surface (the upper air) is a fundamental climate variable.  RSS merges together data from the MSU and AMSU microwave sounders to provide a continuous record of upper air temperature beginning in late 1978 and continuing to the present.  Measurements made at different microwave frequencies or channels are sensitive to the temperature of different atmosheric layers.  RSS currently provides 10 different data products based on microwave sounding measurements.


Ocean surface wind can be measured by microwave radiometers, as well as scatterometers.  The two instruments operate differently and are therefore a good check of value agreement.  10 meter ocean wind speeds are measured by the radiometers, and wind vectors (speed and direction) are measured by WindSat (a polarimetric radiometer) and all scatterometers. Units of measurement are meters/second (m/s).